Epidemiology of injuries during Iran wheelchair basketball professional league: predictive risk factors and prevention strategies

Abstract: Background: Very few studies have investigated athletes with disabilities during a long period of competitions, such as a professional league. Also, there are limited findings related to specific mechanisms and risk factors of injury, and prevention strategies in Wheelchair Basketball. Therefore, the objective of this study was to investigate the rate and characteristics of injuries in the 2021-2022 Iran Wheelchair Basketball League and present prevention strategies. Methods: This retrospective study was conducted after the 2021-2022 (Mar 2021-Sep 2022) competition season. The sample size consists of 36 players, who were randomly selected among 129 players. All the data was processed using SPSS (version 21). Results: 111 injuries were registered, equivalent to 132 per 100 players (95% CI: 100-180) and 8.16 Injuries per 1000 hours of athlete exposure (6.2-9.8). Also, 77.8% occurred during training and 22.2% in competitions. Most injuries affected the fingers and hands (35.13%), and shoulders (22.57%). The most common types of injuries were contusions (30.63%), laceration and skin lesion (23.42%), and muscle spasms (13.51%), in which, half of the injuries were slight (0-1 days), 27.8% (mild 4-7 days), and 22.2% moderate (8-28 days). Also, 66.9% of injuries were new, and 33.1% were recurrent. Most situations and actions leading to injury include quick wheelchair pushing (29.72%), the intense ball hitting (17.14%), and sudden stops or changes of direction of the wheelchair (12.63%). A multiple linear regression analysis (Enter method) demonstrated (R2 Adjusted=0.530) Wheelchair inappropriateness (P=0.015), lack of protective equipment (P=0.028), and previous injury (P=0.003) explained close to 55% of the injury rate. Conclusions: The injury rate during the league period was higher than the amounts reported from Paralympic games. Prevention strategies should be focused on rethinking athletes' pre-season readiness evaluation, return to play assessments and protection equipment technologies.


Introduction
n recent decades, Wheelchair Basketball (WB) has become one of the most popular sports for people with disabilities. 1 Functional classification rules in this sport allow a wide range of persons with different disabilities such as spinal cord injuries, lower limb amputations, polio, and other neuromuscular conditions to compete as a team. 2 Basketball players are the second most injured athletes among wheelchair user's athletes. 2ence, research documents about the epidemiology of sports injuries and prevention strategies should be increased in this para-sport.Injury prevention investigations can help develop, implement, and evaluate injury prevention strategies by studying the incidence and severity of the injury, risk factors, and injury mechanisms. 3ome researchers investigated the epidemiology of injury in Wheelchair Basketball athletes during a short competition period such as a world championship (WC) and Paralympic games (PG). 3,4While, there is very limited research that has reported findings related to athletes with disabilities during a long period of competitions, such as a professional league.Also, there are limited findings related to specific mechanisms, injury risk factors, and prevention strategies in this popular parasport.This study aimed to investigate the epidemiology of injury and identify predictive risk factors in the 2021-2022 Iran Men Wheelchair Basketball League (WBL) and present prevention strategies.

Methods
This retrospective study was conducted after the Iran Men Wheelchair Basketball League (WBL) 2021-2022 competition season (Mar 2021-Sep 2022).The sample size was calculated utilizing the G-Power 3.1 software, with a probability of 0.05 (minimum error type I), statistical power of 0.9 (minimum error type II), and effect size of 0.8 (mean effect).Thus, the minimum sample size was 20 participants.However, we registered 36 athletes representing 30 % of the total players.The study was conducted in accordance with the guidelines of the Declaration of Helsinki and was approved by the Research Ethics Committee of University of Tehran.

Data collection
The injury report form used in this study was adapted from forms used by the International Olympic Committee (IOC) 5 with defined categories for the injury characteristics (anatomical region of injury, type, severity, mechanism, risk factor, and practice/competition).
Three injury prevention specialists recorded injuries through interviews and by reviewing the full details of the injuries suffered -from the beginning of the season to the end of league matches -also, they asked participants to explain the specific action or situation that led to injury (as specific mechanisms of injury) and mention possible factors affecting injury (as specific risk factors) using the options proposed by the researchers.It should be noted, the injury was defined as any musculoskeletal problem or injury during training or competitions that required medical intervention, regardless of its consequences.Also, injury severity was categorized as slight (0-1 day), minimal (2-3 days), mild (4-7 days), moderate (8-28 days), and severe (>28 days). 6,7

Calculation of exposure and injury rate
The athletes' exposure was determined based on the teams' training schedule and the number of matches.All the participants had 5 training sessions weekly, for 24 weeks, during the competition season.Athletematch exposure was calculated by multiplying the number of players on the field by the number of games and athlete-training-day exposure as the number of players per team multiplied by the number of training sessions 8 Athlete-days exposure was calculated by multiplying the number of players registered by the number of days of the league matches. 4The injury rates were calculated as the number of injuries per 100 players and per 1,000 athlete days and were reported with a confidence interval (CI) of 95%. 4 The data's normality was confirmed using the Shapiro-Wilk test.Mean, standard deviation, and percentages were utilized to report data.The relative contributions of injury risk factors to injury rate were estimated using multiple linear regression analysis (Enter method).SPSS (version 21) was used to analyze the data.

Results
The sample consists of 36 WB players, whose demographic characteristics are described in Table 1.Table 2 shows the number of injuries, injury rate, and athletes' exposure time.
Table 7 summarizes the indicators of the injury rate among Iran WBL players through injury risk factors.A multiple linear regression analysis (Enter method) demonstrated (R2 Adjusted=0.530) inadequate physical fitness (P=0.015),lack of protective equipment (P=0.028), and previous injury (P=0.003)explained close to 55% of the injury rate variance.

Discussion
This is the first epidemiologic report of a professional WBL in which musculoskeletal injuries and predictive risk factors for injuries were investigated.The rate of injury was 83.7 injuries per 100 players or 12.12 injuries per 1,000 athlete days, and it was higher during competition than during the training sessions.Almost 60% of injuries occurred in the hand and shoulder.Just over half of the injury types were contusion and laceration and about one-third of injuries occurred during quick wheelchair pushing.Inadequate physical fitness (P=0.015),lack of protective equipment (P=0.028), and previous injury (P=0.003)explained close to 55% of the injury rate variances.
The injury rate among players who play in the Iran WBL was higher (25.5 injuries per 1,000 athlete-days [CI: 20.6-30]) than those reported during the 2012 PGs, with 12.0 (CI: 8.3-16.8)injuries per 1,000 athlete-days, 3 and the 2016 PGs, with 12.8 (CI: 9.5-17.4)injuries per 1,000 athlete-days, 8 and lower than the injury rate reported during the 2018 WBWC with 68.9 injuries per 1,000 athlete-days (CI: 55.4-82.4)4,and what was reported during the 2021 South America WBC with 94.5 injuries per 1,000 athlete-days (CI :75.3-113.7). 5 Also, the training injury rate was lower than the matches injury rate which is consistent with other studies. 9Inconsistent findings could be explained by differences in the competition scheduling (uncompress competition schedule and the longer time interval between league matches) and its sensitivity and importance (international vs national).Also, inconsistent findings could result from the limited definition of injury in this study which emphasized medical intervention.
According to the biomechanics of wheelchair sports, it is expected that hand, wrist, and elbow suffered from more injuries due to involvement in all movements, technical demands, and tolerating repetitive stresses. 101][12] Inconsistent findings could be explained by the differences in competitions level and its technical demands which might cause more physical conflict in high-level matches, with hand-to-hand combats, close battles over possession of the ball, collisions with the opponent's wheelchair, and even fall and more risk of neck and back injuries.
4][15] Thus maybe, WB players with trunk control deficiencies (players with 1 to 2.5 classification) need more recovery time compared to other players.Some studies have demonstrated they are at greater risk of fatigue. 16,17Moreover, coaches should consider longer recovery times for wheelchair user players than athletes who use it only for games.As the classification of athletes progresses toward severe disability, some considerations should be reviewed on an individual basis to reduce the risk of injury to people with more severe disabilities.
In the present study, the most common types of injuries were contusions (23.7%), scratches (13.2%), and muscle spasms (11.9%), respectively.Hollander et al. (2020) reported similar findings but they highlighted muscle spasms as the most common type.In addition, 52% of injuries were traumatic and, 48% of injuries were due to overuse mechanisms.Consistent findings have been reported during the 2012 PGs (65%) 3 while overuse injuries predominated during the 2018 WBWC (52%) 4 and 2021 SAWBC (53.8%) (Bogado et al.,  2023).It seems that both mechanisms of injury (trauma and overuse) are challenging that need to be taken into account for WB injury prevention plans.
Participants of this study reported most of the upper limb injuries occur when driving a wheelchair especially repetitive and rapid wheelchair pushing, and sudden deceleration or change of direction.Consistent with this finding, Hazmel et al. ( 2017) reported consistent findings. 10Prevention strategies have to be addressed the wheelchair pushing techniques in WB, regardless of competition level and technical proficiency, in both professional and amateur athletes.
Also, to identify and correct the altered mechanics in wheelchair users with trunk control deficiencies, biomechanical assessments of the wheelchair pushing pattern should be considered in preventive actions in terms of ergonomic corrections and improvement of physical skills.Altered mechanics, is found to be a risk factor in this population. 13,14ur findings showed inadequate physical fitness, lack of protective equipment, and previous injuries positively associated with injury rate.The link between physical fitness and sports-related injuries has been documented through multiple studies. 18Also, Studies have shown that injury prevention programs improve different components of physical fitness as a modifiable intrinsic risk factor. 19,20Due to the diversity of Wheelchair Basketball players' disabilities, designing injury prevention programs should be considered with an emphasis on dynamic balance in the wheelchair and constant care of shoulder kinetics, especially for wheelchair users with trunk control deficiency.In addition, pre-season physical fitness assessment should be applied through prevention plans.
Moreover, the lack of protective equipment was another indicator of the injury rate.WB is characterized by high-speed plays, sudden changes of direction, and frequent contact and collisions with other athletes.Hence, it could be assumed that part of the injury is related to the nature of the game.But it seems that the prevention strategies should be focused on rethinking protection devices technologies. 21For instance, wearable protection equipment could be added to athletes' suits.
Another interesting finding was that the previous injury was positively associated with the injury rate.Due to the changes along the kinematic chain, including proprioceptive deficits, restricted range of motion, excessive flexibility, and scar tissue formation, past injury has been considered the largest internal risk factor for future injury. 22There is evidence that when motor control is compromised, a past injury has a stronger influence on the likelihood of future injury.Without the proper intervention to restore motor control to its ideal state, the risk of future injury will rise. 23,24The likelihood of future injuries may be influenced by past injuries for brief periods of time, but with the right therapy, the association between past injuries and the likelihood of future injuries changes. 25Hence, prevention strategies should be focused on rethinking the rehabilitation programs and return-to-play assessments to evaluate the readiness of the affected body part in relation to returning to the WB.

Conclusion
We concluded that the injury rate among WB players in Iran professional league was higher than those reported in the PGs but lower than those reported in the WBWC and SAWBC.Most of the injuries were seen on the hand/fingers and shoulder, a third was classified as contusions, and acute injuries constituted a little over half of all reported injuries.The majority of injuries were directly linked to the WB game technique, and one-third were related to wheelchair pushing.Inadequate physical fitness, lack of protective equipment, and previous injury were shown to be the greatest indicators of rate in WB players in professional league Iran.
Funding: This study was not funded by any organization.Competing interests: None declared.Ethical approval: This study was approved by the Ethics Committee of University of Tehran.Reference Number: (IR.UT.SPORT.REC.1402.041).